Borrelia miyamotoi, a spirochete that is genetically related to the species of borrelia that cause relapsing fever, has been detected in all tick species that are vectors of Lyme disease.1,2 It was detected in Ixodes scapularis ticks from Connecticut in 2001 and subsequently has been detected in all areas of the United States where Lyme disease is endemic.

Given the widespread distribution of B. miyamotoi, infection due to this agent should be considered in patients who have been exposed to blacklegged ticks in Canada.

What should be stressed is that there is a key methodological difference between these two studies. The first study in the US was looking at human serology tests to, “provide evidence of B. miyamotoi infection and the prevalence of this infection among people in the United States” (NEJM Jan 27 2013). While the latter study in Canada, was looking at specifically at infections in I. scapularis ticks (rather than humans).

Krause et al. conclude (NEJM Jan 27 2013) “The identification of B. miyamotoi antibody in 18 of our study patients, including seroconversion associated with symptoms in 3 patients, suggests that B. miyamotoi infection may [emphasis added] be prevalent in areas where Lyme disease is endemic in the United States”.

The Canadian study found on overall prevalence of less than 1 % for B. miyamotoi. They also noted:

Few ticks were co-infected, however a third of B. miyamotoi-infected ticks and a quarter of A. phagocytophilum-infected ticks were also infected with B. burgdorferi and co-infections of B. miyamotoi and B. burgdorferi occurred more frequently than would be expected by chance.

Overall these were two very interesting articles to read and further remind me of the importance of regular tick checks while working or playing in the outdoor environment. I particularly like the well summarized conclusion in the Canadian paper with the clinical so what statement:

The relatively limited (though expanding) distribution of blacklegged tick populations in Canada [22,28,29] and the lower prevalence of B. miyamotoi infection in these ticks means that at present the risk of infection of humans in Canada would be lower than in parts of the USA [6]. Nevertheless, our study indicated that B. miyamotoi is present across a wide geographic range in Canada, and clinicians should consider B. miyamotoi infection as a possible diagnosis, alongside Lyme disease, Anaplasmosis, Ehrlichiosis, Babesiosis and arboviral infections, in patients suffering from suspected infectious disease who have potentially been exposed to ticks in Canada.